infection and response

• What is active transport?

  Active transport is the movement of molecules or ions across a cell membrane against their concentration gradient, requiring energy in the form of ATP.
• What are two examples of active transport?

  root hair cells- when minerals move from a lower concentration gradient in the soil to a higher concentration in the root.

  
  

  human gut- when nutrients move from a lower concentration in gut to a higher concentration in the blood so that they can be used for respiration.
• What is the definition of diffusion?

  Diffusion is the process by which particles move from an area of high concentration to an area of low concentration.
• which molecules can and can’t get through the cell membrane?

  can: glucose, amino acids, water

  can’: starch, proteins
• What can make the diffusion rate increase?

  bigger concentration rate, higher temperature, larger surface area
• What is the experiment that shows osmosis at work?

  experiment:

  1. put cylinders of potato in different beakers of concentrations of sugar solution. (eg. 0, 0.2, 0.4… 1mol/dm^3)
  2. measure mass of the potato cylinders then leave one cylinder in each beaker for 24 hours
  3. take out and dry them with a paper towel and weigh them.
  4. if the cylinders have drawn in water via osmosis, they will have increased in mass. If water has been drawn out by osmosis they will have decreased in mass
• osmosis is the movement of water molecules from a region of high water concentration to a region of low water concentration
• errors in the osmosis experiment could include:

  • if potatoes aren’t fully dried, t affects the mass SO make sure to fully dry the potatoes with the paper towel
  • water evaporation could affect the concentration SO put cling film over the top of he beakers
  • amomalies SO repeat the experiment, calculating the mean percentage change in mass at each concentration
• the blood passing next to the alveoli contains its of carbon dioxide and very little oxygen. oxygen diffuses out of the alveolus into the blood. Carbon dioxide diffuses into the alveolus and out of the blood.
• When the blood reaches body cells oxygen is released from the red blood cells and diffuses into the body cells. At the same time, carbon dioxide diffuses out of the body cells and into the blood cells to be carried back to the lungs.
• A chromosome is a long, coiled DNA molecule that carries genetic information.
• A human cell has 23 pairs of chromosomes
• chromosomes carry a large number of genes and are made up of DNA molecules
• human cells have 2 copies of chromosomes each
• binary fission:

  1. the circular DNA + plasmids replicate
  2. the cell gets bigger an the DNA strands move to opposite ends of the cell
  3. the cytoplasm begins to divide and new cell walls begin to form
  4. the cytoplasms divides ad two daughter cell are provide. each cell has one copy of DNA, but can have a variable number of copies of the plasmid.
• mitosis is the stage of the cell cycle where a cell divides into two identical daughter cells. Multicellular organisms use mitosis to grow and replace worn-out cells.

  the end of the cell cycle results in new cells identical to the original cell with the same number of chromosomes.
• growth and DNA replication:

  1. in a cell that’s not dividing, the DNA are all spread out in long strings.
  2. before it divides the cell has to grow and increase the amount of sub cellular structure such as mitochondria and ribosomes.
  3. it then duplicates its DNA and each DNA for x-shaped chromosomes.

  mitosis:

  1. the chromosomes line up at the centre of the cel and cell fibres pull them apart. one set of chromosomes is pulled to each end of the cell and the nucleus divides
  2. lastly, the cytoplasm and cell membrane divide, the cell has now provided two new daughter cells
• differentiation is the process of a cell becoming specialised for its job.
• stem cells are undifferentiated cells that can divide to produce more undifferentiated cells. stem cells can be found in embryos and adult bone marrow. however, stem cells that come from bone marrow are not as useful as embryonic stem cells as they can’t turn into any type of cell, only certain ones
• stem cells are used for:

  • replacing faulty blood cells
  • making insulin- producing cells for diabetes
  • nerve cells for paralysed people
  • make an embryo with the same genetic information
• organelles in a plant cell include:

  • nucleus- stores genetic information
  • cell membrane- controls what goes in and out
  • cytoplasm- where chemical reactions take place
  • mitochondria- site of respiration
  • cell wall: protects and supports the cell
  • chloroplasts- site of photosynthesis
  • vacuole- stores the sugary sap
  • ribosomes- where protein is made
• cell- a basic unit of life from which larger structures can be made

  organelle- feature/structure in a cell

  tissue- a group of specialised cells with similar structure / function, they work together to do a particular job

  organ- made of from a group of tissues which all work together to do a particular job
• stem cell can be used in plants to:

  • produce clones of whole plants quickly + cheaply.
  • grow more plants of rare species (to prevent extinction)
  • grow crops of identical plants that have desired features for example, disease resistance
• stem cells in plants can be found in the meristem tissue of the shoot and root tips. it is able to differentiate into lots of different types of plant cell so it can grow
• the sperm cell is specialised to carry the male genetic information to the egg. it has a streamed head and a long tail it also has lots of mitochondria to transfer energy.

  A) midpiece containing mitochondria

  B) haploid nucleus

  C) acrosome

  D) tail

  
• the nerve cell is specialised to carry electrical impulses around the body. it is long and thin with connections at each end.

  A) cell body

  B) dendrite

  C) axon

  D) nucleus

  E) myelin sheath

  
• the root hair cell is specialised for absorbing water and minerals from the soil. it has a large surface area and no chloroplasts as there is no light underground.

  A) ribosomes

  B) mitochondria

  C) nucleus

  D) cytoplasm

  E) cell membrane

  F) cell wall

  G) root hair

  H) vacuole

  
• the palisade cell is specialised to carry out photosynthesis. it is found at the top surface of leaves, it is paced with chloroplasts, it is thin with a large surface area to absorb more light

  A) cell membrane

  B) chloroplast

  C) cytoplasm

  D) vacuole

  E) nucleus

  F) cell wall

  
• red blood cell is specialised to transport oxygenn around the body. it contains haemoglobin which is a protein that binds to oxygen. it has no nucleus and is disc shaped to increase surface area

  A) cytoplasm containing haemoglobin

  B) cell membrane

  C) biconcave shape due to lack of nucleus

  
• plant cell tissue diagram

  A) epidermal tissue

  B) waxy tissue

  C) palisade mesophyll tissue

  D) xylem

  E) phloem

  F) stomata

  G) guard cell

  H) air space

  I) spongy mesophyll tissue

  
• plant cell tissues:

  • epidermal tissue- covers the whole plant
  • palisade mesophyll tissue- most photosynthesis happens; located in the leaves
  • spongy mesophyll tissue- contains big air spaces to allow gases to diffuse in and out of the cells; located in the leaves
  • xylem and phloem- transport things like water, mineral ions and food around the plant
  • meristem tissue- found at the growing tips of shoots and roots, can differentiate into different types of plant cell to let the plant grow
• a light microscope uses light to see small objects it has a lower magnification + resolution than an electron microscope which uses electrons to see small objects.
• magnification = image size / real size
• microscope diagram

  A) eyepiece

  B) objective lense

  C) fine focus wheel

  D) coarse focus wheel

  E) arm

  F) stage

  G) mirror

  H) condenser

  I) stage clip